Semaphore vs. Mutex

The difference between semaphore and mutex is that semaphore is a signalling mechanism whereas mutex is the locking mechanism.

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Semaphore vs. Mutex

The operating system is the most important concept in computer science, in the operating system, two main concepts are semaphore and mutex. There is a lot of difference between a semaphore and a mutex. If we talk about the main difference, then the main difference between semaphore and mutex is that semaphore is a signalling mechanism whereas mutex is the locking mechanism.

The difference between semaphore and mutex comes in the processes; semaphore performs wait () and signal () operation, this function is responsible for knowing whether they have acquired or they have released the resource.  On the other hand, if we talk about mutex, the mutex is the locking mechanism.

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Semaphore is an integer variable S; semaphore is a signalling mechanism. In an operating system, there is a need for a synchronisation tool, and that tool in the operating system is known as a semaphore. There are two main functions of semaphore that are waiting (), signal (). Semaphore value is changed with two functions that are waiting () and signal (). When a process is using a resource, the semaphore is on wait (), and when the process used the resource, and that resource is free, then the semaphore gives the signal (). These functions that are wait () and signal (), these are used because only one process can use the resource at one time. One resource cannot be given to two processes. There are two types of semaphore in the operating system that are binary semaphore and counting semaphore. In counting semaphore, the initialized value is the number of resources that are available. When a process is using a resource, it faces wait () and has to wait for that resource. Counting semaphore value is decremented one by one. When a process uses a resource, it releases that resource and release signal () so that it must be free for another process. When the count of resources is 0, it means that no resource is available for the coming process. There are two values in binary semaphore that are 0 and 1. When the process is using a resource value of the binary semaphore is from 1 to 0 and when a resource has used the resource then the value of the binary semaphore to 1 to 0.

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The mutex is also known as mutual exclusion object. We know that only one process can use a resource at one time. This is the reason there is a system of locking, and that system of the lock is known as a mutex. Mutex lock is given to a process when that process is using a resource.  Mutex object has a unique name and ID. In a program whenever there is a need of mutex lock, mutex lock is called by its name and ID. If we see the code of mutex, we will have the clear understanding of the implementation and use of mutex lock.

Contents: Difference between Semaphore and Mutex

Comparison Chart

BasisSemaphoreMutex
MeaningSemaphore is a signalling mechanismThe mutex is a locking mechanism.
ValueSemaphore is an integer.A mutex is an object.
OperationOperations of semaphore wait () and signal ().Operations of mutex are lock and unlock
TypesTwo types of semaphore are counting semaphore and binary semaphore.There are no types of a mutex lock.

 Semaphore

Semaphore is an integer variable S; semaphore is a signalling mechanism. In an operating system, there is a need for a synchronization tool, and that tool in the operating system is known as a semaphore. There are two main functions of semaphore that are waiting (), signal (). Semaphore value is changed with two functions that are waiting () and signal (). When a process is using a resource, the semaphore is on wait (), and when the process used the resource, and that resource is free, then the semaphore gives the signal (). These functions that are a wait () and signal (), these are used because only one process can use the resource at one time.

One resource cannot be given to two processes. There are two types of semaphore in the operating system that are binary semaphore and counting semaphore. In counting semaphore, the initialised value is the number of resources that are available. When a process is using a resource, it faces wait () and has to wait for that resource. Counting semaphore value is decremented one by one. When a process uses a resource, it releases that resource and release signal () so that it must be free for another process. When the count of resources is 0, it means that no resource is available for the coming process. There are two values in binary semaphore that are 0 and 1. When the process is using a resource value of the binary semaphore is from 1 to 0 and when a resource has used the resource then the value of the binary semaphore to 1 to 0.

 Mutex

The mutex is also known as mutual exclusion object. We know that only one process can use a resource at one time. This is the reason there is a system of locking, and that system of the lock is known as a mutex. Mutex lock is given to a process when that process is using a resource.  Mutex object has a unique name and ID. In a program whenever there is a need of mutex lock, mutex lock is called by its name and ID. If we see the code of mutex, we will have the clear understanding of the implementation and use of mutex lock.

Key Difference

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  1. Semaphore is a signalling mechanism whereas Mutex is the locking
  2. Semaphore is an integer whereas Mutex is an object.
  3. Operations of semaphore wait () and signal () whereas Operations of mutex are lock and unlock.
  4. Two types of semaphore are counting semaphore and binary semaphore whereas there are no types of a mutex

Conclusion

In this article above we see the clear difference between semaphore and mutex with their proper implementation.

Explanatory Video

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